“Diamonds are forever” is a clever jewelry marketing slogan, a popular James Bond film and the thing that helped geologists find a long lost of an ancient arctic continent that once stretched from Scotland to Labrador, Canada. What’s the bigger deal – the chunk or the diamonds?
“For researchers, kimberlites are subterranean rockets that pick up passengers on their way to the surface.”
Wait a minute … you said this story was about rocks, not rockets and passengers from the center of the Earth!
“The passengers are solid chunks of wall rocks that carry a wealth of details on conditions far beneath the surface of our planet over time.”
University of British Columbia geologist Maya Kopylova metaphorically describes how igneous rocks called kimberlites pick up diamonds and other ‘passengers’ as they are brought from deep underground to the surface by geological forces. Kopylova and colleagues were studying kimberlites from Baffin Island in Nunavut, specifically from a De Beers Chidliak Kimberlite Province property (and yes, De Beers created the ‘Diamonds are forever’ slogan – see how all of this is connected?). While De Beers obviously wanted them looking for signs of diamonds, the team noticed that the mineral composition of these rocks showed that they belongs to the North Atlantic Craton – which sounds like a movie monster but is actually ancient form of continent. Some parts of this craton eventually became part of North America and Greenland, but others sank beneath the Earth’s crust, never to be seen again.
Never underestimate the lure of diamonds.
“Finding these ‘lost’ pieces is like finding a missing piece of a puzzle. The scientific puzzle of the ancient Earth can’t be complete without all of the pieces.”
In a press release by the University of British Columbia announcing the paper published in Journal of Petrology, lead author Kopylova describes why geologists are so excited about this find. Cratons are billion-year-old parts of the continental lithosphere – the combined ancient crust and upper mantle that eventually broke up to form today’s continents and tectonic plates. The North Atlantic Craton is one, as are the North China Craton, the Sarmatian Craton in Russia and Ukraine, the Amazonia Craton in South America, the Kaapvaal Craton in South Africa and the Gawler Craton in South Australia. Each has its own unique mineral structure which help identify them.
Also called Laurentia, the North Atlantic Craton has had its ups and downs over time, forming parts of early continents and supercontinents. Laurentia is named after the Laurentian Shield, a large area of exposed igneous and high-grade metamorphic rocks that make its area an excellent place for mining minerals and diamonds. How important are these pieces of the Laurentia puzzle?
“With these samples we’re able to reconstruct the shapes of ancient continents based on deeper, mantle rocks. We can now understand and map not only the uppermost skinny layer of Earth that makes up one percent of the planet’s volume, but our knowledge is literally and symbolically deeper. We can put together 200-kilometre deep fragments and contrast them based on the details of the deep mineralogy.”
Believe it or not, while De Beers is obviously on Baffin Island for the diamonds, this is actually part of a graduate student project at the University of British Columbia to help train future geologists. UBC students get samples to study, De Beer gets maps to future diamond mines and Kopylova gets more data to add to the early history of Earth.
And those looking for movie monster ideas get a good one: The North Atlantic Craton Meets Godzilla at the North Pole!